US20050252334A1 - Pedal assembly - Google Patents

Abstract

A pedal assembly including a bracket, a pedal lever pivotally mounted to the bracket, a spring mounted to the bracket, and a cam pivotally mounted to the bracket. The cam engages one end of the spring so as to load the spring while the came pivots. The cam has a pre-determined profile and the pedal lever engages the cam profile to pivot the cam and load the spring during the stroke of the pedal lever, thus enabling the assembly to provide a pre-determined force versus stroke profile.

Description

FIELD OF INVENTION
• The invention relates to the art of pedal assemblies.
BACKGROUND OF INVENTION
• Pedal assemblies for controlling clutches often use an over-the-center spring mechanism to generate an initial force which resists the activation of the pedal. Once the pedal passes over the center of the mechanism, the spring assists somewhat in activating the pedal.
• The problem with this solution is that the shape of the force vs. stroke profile is generally constrained. In some applications, the force vs. stroke profile cannot be adequately provided by an over-the-center spring mechanism.
• A more robust solution is desired. In particular, it would be especially useful to tailor the force vs. stroke profile to the needs of any particular application.
SUMMARY OF INVENTION
• According to one aspect of the invention a pedal assembly is provided which includes a bracket; a pedal lever pivotally mounted to the bracket; a spring mounted to the bracket; and a cam pivotally mounted to the bracket. The cam engages one end of the spring so as to load the spring as the cam pivots. The cam has a predetermined cam profile and the pedal lever engages the cam profile to pivot the cam and load the spring during the stroke of the pedal lever. The cam profile enables the force vs. stroke profile to be more readily tailored for ant given application.
BRIEF DESCRIPTION OF DRAWINGS
• The foregoing and other aspects of the invention will be better understood from the following detailed description of preferred embodiments thereof in conjunction with the drawings, wherein:
• FIG. 1 is a perspective view of a pedal assembly according to a preferred embodiment of the invention;
• FIG. 1A is detailed view of the pedal assembly shown in FIG. 1;
• FIG. 2 is fragmentary perspective view of the pedal assembly shown in FIG. 1, with a bracket removed from the illustration;
• FIG. 3 is another fragmentary perspective view of the pedal assembly, with brackets, pedals and other supporting structure removed from the illustration; and
• FIG. 4 is a graph showing the force vs. stroke profile of the preferred embodiment in relation to a prior art over the center toggle mechanism.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
• FIG. 1 shows a pedal assembly 10 comprising a pedal lever 14 pivotally mounted to a bracket 12 about axis 16 as well known in the art. A roller 18 is mounted to the pedal lever 14.
• The bracket 12 includes sub-brackets 20 and 22 which are rigidly connected to bracket 12 to form a box-like enclosure. The sub-brackets 20, 22 carry a shaft 24 along an axis 25, which is oriented generally perpendicular to the pedal rotational axis 16. A torsion spring 26 is mounted on the shaft 24. In addition, a cam 30 is journal-mounted to the shaft 24 so as to be rotatable about axis 25. As seen best in FIG. 4, one end 28 of spring 26 bears against the cam 30 and, as seen best in FIG. 1A, the other end 27 of the spring bears against the sub-bracket 20.
• The cam 30 features a cam profile 32, seen best in FIG. 4. The roller 18, which functions as a cam follower, bears against the cam profile 32. When the pedal is in the rest position, the roller 18 is located in an initial position shown in FIG. 4. Due to the initial bulge 32A in the cam profile 32, activating the pedal lever 14 causes the roller 18 to push the cam upward (in a direction generally transverse to both axes 16 & 25) and twist spring 26. Consequently, a substantial force is required to initially activate the pedal. This force is related to the torsion characteristics of the spring rather the compression characteristics of the spring, and hence a generally sharper force vs. stroke profile 40 can be achieved, as seen in the comparison graph of FIG. 4, as compared to a prior art over-the-center toggle mechanism profile 42. Once the roller passes the bulge 32A, the spring 26 assists in the activation of the pedal lever 14. However, unlike the prior art, the cam profile 32B enables the assist force provided by the torsion spring 26 to be tailored to a predetermined profile.
• In alternative embodiments, a compression spring may be used instead of a torsion spring. For example, a sub-bracket may be mounted above the cam with a spring extending between the bracket and the cam that would be compressed as the cam pivots upward. Those skilled in the art will understand that a variety of other modifications may be made to the embodiments described herein without departing from the spirit of the invention.

Claims (4)

1. A pedal assembly, comprising:

a bracket;

a pedal lever pivotally mounted to the bracket;

a spring mounted to the bracket; and

a cam pivotally mounted to the bracket, the cam engaging one end of the spring so as to load the spring as the cam pivots;

wherein the cam has a pre-determined cam profile and the pedal lever engages the cam profile to pivot the cam and load the spring during the stroke of the pedal lever.

2. A pedal assembly according to claim 1, wherein the pedal lever includes a roller for engaging and following said cam profile.

3. A pedal assembly according to claim 1, wherein the pedal lever pivots about a first axis and the cam pivots about a second axis that is oriented transverse to the first axis.

4. A pedal assembly according to claim 1, wherein the cam twists the spring.

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